983
FXUS06 KWBC 011918
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI SEPTEMBER 01 2023
6-10 DAY OUTLOOK FOR SEP 07 - 11 2023
THERE IS GOOD AGREEMENT AMONG THE MODELS WITH RESPECT TO THE PREDICTED MEAN
500-HPA HEIGHT PATTERN ACROSS NORTH AMERICA DURING THE 6 TO 10 DAY PERIOD.
MID-LEVEL HIGH PRESSURE IS FORECAST OVER THE NORTH PACIFIC, ASSOCIATED WITH
POSITIVE 500-HPA GEOPOTENTIAL HEIGHT ANOMALIES ACROSS THE ALEUTIANS. SLIGHTLY
NEGATIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS MAINLAND ALASKA. A WEAK
MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC DE-AMPLIFIES DURING THE PERIOD,
RESULTING IN MEAN NEAR NORMAL 500-HPA HEIGHTS FOR SOUTHEAST ALASKA AND PARTS OF
THE PACIFIC NORTHWEST. ALL ENSEMBLE MODELS FAVOR MID-LEVEL HIGH PRESSURE AND
POSITIVE 500-HPA HEIGHT ANOMALIES OVER MOST OF THE CONTIGUOUS UNITED STATES
(CONUS), WITH THE EXCEPTION OF THE SOUTHEAST, WHERE A WEAK TROUGH IS FORECAST
NEAR THE ATLANTIC COAST.
BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS THE ALASKA PENINSULA AND MUCH OF
MAINLAND ALASKA, UNDERNEATH MID-LEVEL LOW PRESSURE. UNDERNEATH A DE-AMPLIFYING
MEAN MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC AND NEAR NORMAL 500-HPA
HEIGHTS, NEAR NORMAL TEMPERATURES ARE FAVORED FOR SOUTHEAST ALASKA AND THE
PACIFIC NORTHWEST. MID-LEVEL HIGH PRESSURE STRETCHING FROM THE SOUTHWESTERN TO
THE NORTHEASTERN CONUS LEADS TO ENHANCED CHANCES OF ABOVE-NORMAL TEMPERATURES
FROM SOUTHERN CALIFORNIA, THE GREAT BASIN, AND THE NORTHERN ROCKIES, IN THE
WEST, TO THE ATLANTIC COAST.
AHEAD OF A MEAN MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC, ABOVE NORMAL
PRECIPITATION IS FAVORED FOR SOUTHEAST ALASKA. ELSEWHERE IN ALASKA, A STRONG
PRESSURE GRADIENT BETWEEN MID-LEVEL HIGH PRESSURE OVER THE NORTH PACIFIC AND
LOW PRESSURE OVER THE ARCTIC PROMOTES AN ACTIVE STORM TRACK, FAVORING SLIGHTLY
ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION ACROSS MOST OF THE STATE.
ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FROM THE NORTHERN PLAINS THROUGH THE
OHIO VALLEY INTO THE NORTHEAST, SUPPORTED BY MOST DYNAMICAL MODEL FORECAST
TOOLS. ELSEWHERE ACROSS THE LOWER 48, INCLUDING THE WEST, THE SOUTHERN PLAINS,
THE GULF COAST, AND THE NORTH-CENTRAL GREAT LAKES, NEAR TO BELOW NORMAL
PRECIPITATION IS PREDICTED, SUPPORTED BY THE PRECIPITATION CONSOLIDATION.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 45% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, AND 55% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG DYNAMICAL MODEL SOLUTIONS IN THE PREDICTED MEAN MID-LEVEL
HEIGHT PATTERN ACROSS NORTH AMERICA, OFFSET BY MODEL UNCERTAINTY IN THE
PREDICTED TEMPERATURE AND PRECIPITATION.
8-14 DAY OUTLOOK FOR SEP 09 - 15 2023
DURING THE 8 TO 14 DAY PERIOD (WEEK 2), POSITIVE 500-HPA GEOPOTENTIAL HEIGHT
ANOMALIES ARE PREDICTED ACROSS THE WESTERN CONUS IN THE MANUAL BLEND OF MODELS,
AND A WEAK TROUGH IS FORECAST OVER THE EAST COAST. A 500-HPA RIDGE OF HIGH
PRESSURE THAT IS FORECAST OVER THE NORTH PACIFIC AND THE ALEUTIANS IS FORECAST
TO SHIFT WESTWARD RELATIVE TO YESTERDAY’S FORECASTS. BELOW NORMAL MEAN
MID-LEVEL HEIGHTS ARE FAVORED ACROSS MAINLAND ALASKA, WITH POSITIVE 500-HPA
HEIGHT ANOMALIES OVER SOUTHEAST ALASKA. THERE IS SOME DISAGREEMENT BETWEEN
TODAY’S GEFS AND ECMWF ENSEMBLE MODEL SOLUTIONS WITH RESPECT TO THE STRENGTH
AND LOCATION OF THE NORTH PACIFIC RIDGE, ADDING SOME UNCERTAINTY TO THE
FORECAST FOR ALASKA.
BELOW NORMAL TEMPERATURES ARE FAVORED FOR SOUTHWESTERN ALASKA, UNDER NEGATIVE
500-HPA HEIGHT ANOMALIES. NEAR NORMAL TEMPERATURES ARE FORECAST OVER REMAINING
AREAS OF THE STATE, WITH INCREASING UNCERTAINTY IN THE CIRCULATION PATTERN.
WEAK PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE INDICATED ACROSS THE
PACIFIC NORTHWEST, UNDERNEATH RISING MID-LEVEL HEIGHTS DURING THE PERIOD.
ACROSS THE REMAINDER OF THE CONUS, THERE ARE ENHANCED PROBABILITIES OF ABOVE
NORMAL TEMPERATURES IN TODAY’S WEEK-2 FORECAST, ASSOCIATED WITH A BROAD REGION
OF MID-LEVEL HIGH PRESSURE OVER THE WEST AND NORTHERN TIER.
NEAR TO BELOW NORMAL PRECIPITATION IS FAVORED FOR THE WESTERN CONUS, UNDER
POSITIVE 500-HPA HEIGHT ANOMALIES, AND ALONG THE GULF COAST, SUPPORTED BY THE
PRECIPITATION CONSOLIDATION. IN A PATTERN SIMILAR TO THE FORECAST FOR THE 6-10
DAY PERIOD, ABOVE NORMAL PRECIPITATION IS FAVORED FROM THE NORTHERN PLAINS
ACROSS THE OHIO VALLEY INTO THE NORTHEAST, SUPPORTED BY THE PRECIPITATION
CONSOLIDATION OF MODEL FORECASTS. IN ALASKA, AN ACTIVE STORM TRACK IS PREDICTED
TO PERSIST, FAVORING INCREASED CHANCES OF ABOVE NORMAL PRECIPITATION FOR MOST
OF THE STATE.
AVERAGE, 3 OUT OF 5, DUE TO GOOD AGREEMENT AMONG THE MODELS IN THE PREDICTED
MID-LEVEL HEIGHT PATTERN ACROSS NORTH AMERICA, BUT WITH SOME INCREASED
UNCERTAINTY WITH RESPECT TO THE EVOLUTION OF THE OVERALL PATTERN, AND
DIFFERENCES AMONG THE MODEL TEMPERATURE AND PRECIPITATION TOOLS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 45% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, AND 55% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG THE MODELS IN THE PREDICTED MID-LEVEL HEIGHT PATTERN ACROSS
NORTH AMERICA, BUT WITH SOME INCREASED UNCERTAINTY WITH RESPECT TO THE
EVOLUTION OF THE OVERALL PATTERN, AND DIFFERENCES AMONG THE MODEL TEMPERATURE
AND PRECIPITATION TOOLS.
FORECASTER: D COLLINS
NOTES:
AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES. IN
THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT ISSUED.
THE NOTATION FOR THE CATEGORICAL FORECAST INDICATED ON THE MAPS IS THE SAME AS
THAT IN THE TABLES: A-ABOVE N-NEAR NORMAL B-BELOW
THE TEMPERATURE MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WARMER (ORANGE,
"A"), COLDER (BLUE, "B"), OR CLOSE TO (UNSHADED, "N"). HISTORICAL AVERAGE
VALUES FOR THE CALENDAR PERIOD OF THE FORECAST (DASHES, "F"). LABELS ON THE
SHADED LINES GIVE THE PROBABILITY (> 33%) OF THE MORE LIKELY CATEGORY (B OR A).
PROBABILITY OF N IS ALWAYS < 40%.
THE PRECIPITATION MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WETTER (GREEN,
"A"), DRIER (TAN, "B"), OR CLOSE TO (UNSHADED, "N"). HISTORICAL MEDIAN VALUES
FOR THE CALENDAR PERIOD OF THE FORECAST (DASHES, "INCHES"). LABELS ON THE
SHADED LINES GIVE THE PROBABILITY (> 33%) OF THE MORE LIKELY CATEGORY (B OR A).
PROBABILITY OF N IS ALWAYS < 40%.
IN THE SOUTHWEST AND OTHER CLIMATOLOGICALLY DRY REGIONS - THERE WILL BE A
GREATER THAN 33.3% CHANCE OF NO PRECIPITATION AND OCCASIONALLY EVEN A NORMAL
(I.E. MEDIAN) VALUE OF ZERO - ESPECIALLY DURING THE DRY SEASONS. IN SUCH CASES
A FORECAST OF NEAR NORMAL IS EFFECTIVELY A FORECAST OF LITTLE OR NO
PRECIPITATION.
THE CLIMATE PREDICTION CENTER USES 1991-2020 BASE PERIOD MEANS AS REFERENCE IN
THE CLIMATE OUTLOOKS.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON
SEPTEMBER 21.
ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
19910816 - 19890903 - 19860830 - 19900914 - 19570826
ANALOGS TO THE 7 DAY MEAN OBSERVED PATTERN CENTERED 4 DAYS AGO (D-4)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 7 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
19890820 - 19890903 - 19910815 - 19900914 - 19570825
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 07 - 11 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N B OREGON N B NRN CALIF N N
SRN CALIF A N IDAHO A N NEVADA A B
W MONTANA A N E MONTANA A N WYOMING A N
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A N
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A B WISCONSIN A N
ILLINOIS A A MISSISSIPPI A B MICHIGAN A N
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A B NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A N GEORGIA A N
FL PNHDL A B FL PENIN A B AK N SLOPE N A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 09 - 15 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A N WYOMING A N
UTAH A B ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A N S TEXAS A B W TEXAS A B
MINNESOTA A N IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A B WISCONSIN A N
ILLINOIS A A MISSISSIPPI A N MICHIGAN A N
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A N NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A N
FL PNHDL A B FL PENIN A B AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B A AK INT BSN N A
AK S INT B A AK SO COAST N A AK PNHDL N A
LEGEND
TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN
A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN
B - BELOW B - BELOW
THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.
FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS
PMDMRD.
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